11/29/2010 PERMALINK
A molecular switch found that controls both memory and addiction. SOURCE : Learning and memory formation are based on the creation of new connections between neurons in the brain. Also, behaviors such as nicotine addiction manifest themselves in long-term changes of neuronal connectivity and can – at least in this respect – be viewed as a form of learning. A team around Pierluigi Nicotera, scientific director of the German Center for Neurodegenerative Diseases (DZNE) and collaborating laboratories at the MRC, UK and University of Modena, Italy have now discovered a molecular switch that plays a crucial role in establishing addictive behavior and memory processes. The scientists found that nicotine administration to mice induces the expression of a gene called type 2 ryanodine receptor (RyR2). RyR2 protein is involved in releasing calcium from a cell internal calcium store, the endoplasmic reticulum, thus leading to a long-lasting reinforcement of calcium signaling in a self-sustained manner. This sustained calcium-increase then leads to neuronal plasticity. Specifically, RyR2 is expressed in a number of brain areas associated with cognition and addiction as the cortex and ventral midbrain, suggesting that RyR2 induction plays a pivotal role in these processes. This idea was confirmed in an additional experiment, in which the authors of the study demonstrate that a reduction of RyR2-activation in living animals abolishes behavior associated with learning, memory and addiction. This shows that RyR2 is absolutely required to develop long-term changes in the brain that lead to addiction.